The present invention relates generally to safety cages for ladders. More particularly, the invention relates to a slideably retractable safety cage enclosure that can be mounted either to the ladder itself or a wall, and can provide a safety enclosure around the top of the ladder to prevent passersby from falling in near the opening.
Fixed ladders find wide utility throughout industry, generally in permanent installations where periodic access to a different level is required for the purposes of maintenance, equipment operation, equipment inspection, or the like. Such fixed ladders are most often used in situations where sufficient lateral space is not available to enable the use of more conventional stairways, or where the frequency or type of use does not economically dictate employment of these more conventional stairways. Fixed ladders find particular applicability when mounted on the side of manholes or other vertical tunnels; to the exterior or interior of fluid containing tanks; or to the exterior or interior of buildings, towers, or other set structures. Manhole ladders that are permanently fixed to the inside wall of a manhole are typically wholly located within the manhole below its upper rim so that the manhole entrance can be covered with a manhole plate or grate. The fact that the ladder does not extend above the manhole entrance makes it difficult for a user to mount and dismount the top end of the ladder. Therefore, the manhole user must support and balance himself from the rim of the manhole during entry until his body is almost entirely within the manhole. Only then can the user grasp the top rung of the manhole ladder. This safety problem occurs upon exiting the manhole as well. This entry and exit situation is dangerous since users can slip and fall during these maneuvers. This danger is augmented in normal operation when the user must carry tools, equipment, and the like into and out of the manhole.
A further complication of these types of fixed ladders is that when the manhole opening is uncovered for use of the ladder, the opening itself presents a danger to anyone in the vicinity. In particular, the result of the typical manhole design is that when the cover is open, the hole is completely exposed and presents a fall hazard for passersby. For safety purposes, users typically must place some sort of warning sign or barricade, or must rope off the opening to alert persons in the vicinity that such fall hazard exists.
Several prior art devices have attempted to solve some of the many problems inherent in manhole design. The majority of the prior art devices have addressed the safety issues related to the ladder user, while failing to address the safety issues related to the manhole opening. In general, some of these devices provide a rail or auxiliary support that is extendable from the ladder so that the ladder user can grasp this extended rail, thus improving his balance and stability while entering and exiting the manhole. These prior art devices, while perhaps assisting the ladder user, have proven to be cumbersome, complicated to use, and time-consuming. In addition, these devices often defeat the purpose of fixed vertical ladders in that the safety devices have fixed, vertically-extending members that, when retracted, occupy an inordinate amount of space near the upper end of the manhole ladder within the manhole. This arrangement impedes user operation and versatility of the manhole. Furthermore, many manholes simply do not have the space required of the extendable supports of the prior art devices. In addition, many entities (for instance, cities, municipalities, industrial work sites, and so forth) own so many manholes that they choose not to purchase prior art safety cages as a result of the extreme costs involved in purchasing a separate safety cage for each and every manhole.
In short, prior art devices have failed to address the needs of both the ladder user and persons in the vicinity of the ladder or manhole opening. In particular, prior art devices do not adequately provide both an extendable safety support for the ladder user and a retractable safety cage that provides an adequate enclosure around the opening to prevent accidental falling into the opening. And, prior art devices have not provided a safety cage that can be completely, but easily, removed from the manhole.
As a result, there is a need for a retractable safety cage device that provides adequate safety support for a user entering and exiting a ladder opening, while at the same time providing a safety enclosure for completely protecting the opening of the manhole, thus providing safety for all persons in the vicinity. There is a further need for such a device that can accomplish these goals while at the same time being mountable on either the ladder itself or the vertical wall, and which does not block or impede the ladder entrance or the space surrounding the top of the ladder. And, there is a need for a safety cage that can be removed from the manhole so that one cage can be employed in numerous manholes that are fitted with the guide bracket.
Accordingly, the present invention is directed to a retractable safety cage device that is mounted on or near the top of a ladder and provides an extendable support for the ladder user, as well as a retractable safety cage to protect the opening near the top of the ladder. The device is mounted either on the ladder or on a structure near the ladder and does not block or impede the space near the top of the ladder in either its extended or retracted position. The invention is usable not only in ladder applications, but also in access holes and access ports that have no ladder therein. An example of such a situation is a subsurface observation port, for instance a maintenance pit observation port, and other ports where, for safety reasons, persons are not allowed inside the pit while the subterranean machinery is in operation. Other pits that find use for the invention are pits containing hazardous materials, drive motors, rotating machinery, and so forth where persons must be able to view the machinery from above the surface of the pit without physically descending into the pit. In such situations, the need exists for a retractable safety cage that, in its extended position, provides a safety enclosure around the opening to prevent persons from falling into the pit. Additionally, the device has the ability to be retractable in a permanent installation or in a removable installation, depending on the needs of the user.
A retractable safety cage for mounting on a wall or a ladder is provided comprising one or more adjustable guide brackets attached to either the wall or the ladder wherein the guide brackets have a portion containing a sleeve through which a rail can slide. At least two main, typically vertical, rails each having a proximal end and a distal end are slideably mounted within the sleeves of the adjustable guide brackets for sliding between a retracted position and an extended position. A locking mechanism is further provided that can releasably lock the retractable safety cage in either the extended or the retracted position. Furthermore, one or more counterbalances are provided that provide a bias force in the direction of the extended position of the retractable safety cage. In addition, a fixed first periphery rail having a first end and a second end each connected to the proximal end of the main rails, is attached to the main rails.